In many scientific applications it is desirable to quickly and accurately measure fluctuating electrical or magnetic stimuli, such as voltage, current, electrical field or magnetic field. It is often necessary to accomplish these measurements at widely varying frequencies. Heretofore, one of the best methods of achieving quick, accurate measurements of electric and/or magnetic stimuli over a wide bandwidth is to utilize one of several types of transducers which employ electro-optic or magneto-optic effects to modulate the intensity of a beam of light in proportion to the measured electrical or magnetic stimulus. Typically the electro-optic or magneto-optic transducer would be placed between crossed polarizers and a beam of light then transmitted through the optical components, including the transducer, to a detector. The application of the electrical or magnetic stimulus to be measured to the transducer induces a realignment of the light waves incident on the second polarizer and thus a change of light intensity of the light beam passing through the entire system. Since the intensity of the light is proportional to the applied electrical or magnetic stimulus, the stimulus is thus effectively measured. Unfortunately, such electro-optic or magneto-optic transducers have a largely non-linear response, and thus it is difficult to tell in an environment subject to rapidly fluctuating stimuli exactly which level of stimulus is being measured. Typically, existing electro-optic and magneto-optic systems are linear in their response over the very small range of plus or minus onesixth of the transducer constant.
Accordingly, it often is necessary to employ computers with existing systems in order to better predict which level of stimulus is being measured at a particular time; that is to say, where on the response curve the system is operating. Unfortunately, the insertion of a computer in the system operates to limit the bandwidth and accuracy of the system to the bandwidth and accuracy of the computer, and further adds to the cost and complexity of the system.
If the linear operating range of the electro-optic or magneto-optic transducers could be extended, then applied electrical or magnetic stimuli could be measured directly without the use of a costly computer system, with no loss of bandwidth or accuracy and at greatly reduced cost. There would also be no loss of speed of measurement on account of the necessity of employing additional equipment in the system, and the system could be built more cheaply.